Forensic scientists have said that around 80% of all British banknotes contain traces of drugs. A 1999 study found even higher levels of contamination in the London area; of 500 notes tested, only four had no traces of cocaine. Most of the banknotes showed only low levels of contamination, suggesting they had merely been in contact with contaminated notes, but 4% of the notes in the study showed higher levels, which the researchers suggested was the result of either being handled by people under the influence of cocaine (which is excreted in skin oils), or by being used directly to snort the drug.
There are drug levels above which banknotes need to be taken out of circulation, and over £15 million worth of notes are destroyed annually for this reason. The destruction is more often done as a precaution than because the money poses a serious health hazard.
Cocaine is the drug most commonly found on banknotes. Heroin and ecstasy are found less often, though the frequency of ecstasy contamination rose in the years leading up to 2002. Joe Reevy of Mass Spec Analytical, a company which analyses confiscated banknotes for the police, pointed out that heroin and ecstasy degrade more rapidly than cocaine, and that a single note which had been used to snort cocaine could subsequently contaminate many others when placed in a sorting machine, to explain the frequency of cocaine contamination.
Money recovered from police raids on the drugs trade are often heavily contaminated. In one raid in 2002, £465,000 was found which had been stored in a room where heroin was being prepared, and was so heavily contaminated that officers were advised not to touch it without protective equipment.
Prior studies found that the level of contamination - i.e., the concentration of the contaminants - was different between those notes suspected to be used in the drug trade and those of proximity transfer levels. Subsequent tests have confirmed this determination, and serve as the basis for court cases against drug dealers, since the basic level of drug contamination remains fairly constant throughout the UK, despite factors that might immediately be thought to affect levels, like rural or urban environments, rich or poor or areas with high or low crime rates.
The contamination of paper money is not limited to simply that of cocaine and other illicit drugs. Health officials in the UK warn that a silent Hepatitis-C epidemic could be brewing. Drug users with hepatitis who share with others the rolled paper note (or straw) used to snort cocaine can facilitate the transfer of the disease to thousands. As drug users are frequently impaired, they can easily fail to notice small traces of blood on these rolled banknotes. This is considered to be of particular concern, as eight out of ten carriers are unaware of their status (as hepatitis can lie dormant for decades), and have little in the way of access to regular healthcare . This higher risk for contracting hepatitis-C has also been noted by the American National Institutes of Health (NIH). Without treatment, hepatitis-C can lead to chronic liver disease.
The British Department of Health estimates that there are over 200,000 people infected with hepatitis C in Britain, but the number might be much higher. Charles Gore, the chief executive of the Hepatitis C Trust, said: "Estimates show that around 5,000 new cases of hepatitis C are diagnosed every year - but they are mainly through chance. Because so many are undiagnosed we can't tell what kind of problem we are looking at. When 5,000 banknotes were tested in London in 2000, 99% of them had traces of cocaine on them. That tells us that there is potentially a massive problem in diagnosis and people's awareness of how easily hepatitis C can be contracted."
Professor Graham Foster, of St Mary's Hospital, London, said: "Sharing banknotes or straws is a significant risk factor that people need to be more aware of. Although the risk of contracting hepatitis C through snorting is lower than through sharing a needle, it is still there."